# New independent testing confirms Hardide-A coating improves fatigue life

- Link: https://www.directorstalkinterviews.com/new-independent-testing-confirms-hardide-a-coating-improves-fatigue-life/412794883
- Published: 2019-10-07T12:43:55+01:00
- Author: Amilia Stone

New independent testing has proven that Hardide-A tungsten carbide/tungsten metal
matrix composite coating improves the fatigue life of metal components by 4.5% when
compared to uncoated substrates.

Hardide-A also eliminates the need for costly secondary shot peening making the 
coating a significant advancement in materials optimisation for the aerospace and
other industries where fatigue debit of surface coated metals is a problem.

The tests were conducted by Westmoreland Mechanical Testing and Research Ltd (WMTR),
a leading aerospace qualified testing laboratory in the UK and USA.

WMTR used the Rotating Bend Fatigue test method complying to BS ISO 1143:2010. This
test is considered to be the most sensitive to the effects of surface treatment 
on fatigue properties. Samples of S99 steel were coated with Hardide-A to a thickness
of 63-70 microns and hardness of ~950 Vickers, which are mid-value thickness and
hardness properties for this coating type. The test was discontinued after 15 million
cycles.

Traditionally, the fatigue debit after hard coatings such as hard chrome plating(
HCP) and HVOF coatings have been applied can be as much as 60% and only following
shot peening of the coated surface can this be reduced to around a 20% debit. The
Hardide-A coating recorded a fatigue life increase of +4.5% after coating without
any need for shot peening. The Wöhler S-N curve for the coated samples is clearly
positioned above the uncoated control samples’ curve by ~40 MPa throughout the whole
range of the N cycles to failure.

Fatigue debit of surface-coated metals has been a long-standing problem for the 
aerospace industry – Hardide-A was developed specifically to meet the needs of the
sector. This environmentally compliant and technically superior replacement for 
HCP and HVOF coatings provides enhanced protection against corrosion and chemically
aggressive media, wear, galling, fretting and fatigue.

> Dr Yuri Zhuk, technical director at Hardide Coatings commented: “Metal fatigue
> is an enduring problem in aerospace as well as for the steam, and industrial gas
> turbines industries and we recognised the value in commissioning independent testing
> to verify the fatigue advantages of Hardide-A.
> “The positive 4.5% improvement to fatigue life provides the detailed analysis 
> and assurance that our solution is an improved alternative to traditional HCP 
> and HVOF coatings. Unlike these other coatings, Hardide-A has no through micro-
> porosity, so creating an excellent barrier against corrosion as well as improving
> fatigue performance.”

Hardide nanostructured coatings have been approved by Airbus, BAE Systems and Leonardo
Helicopters. Applied by low temperature chemical vapour deposition (CVD), they can
coat both internal and external surfaces, and complex geometries. Hardide coatings
can be applied to a wide range of metallic substrates including ferrous and nickel-
based alloys, and most grades of stainless and carbon steels. This enabling technology
is proven to offer dramatic improvements in component life, particularly when applied
to components that operate in very aggressive environments. This results in cost
savings through reduced downtime and increased operational efficiency.

Note to editors:

Hardide Coatings is a **Hardide plc** (LON:HDD) group company. It develops, manufactures
and applies advanced tungsten carbide coatings to a wide range of engineering components.
Its patented technology is unique in combining, in one material, a mix of toughness
and resistance to abrasion, erosion and corrosion together with the ability to coat
accurately interior surfaces and complex geometries.

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